Drying cellulose films



Nov 16 1926.

, 1,606,824 J. E. BRANDENBERGER DRYING CELLULO SE FILMS Filed Jan. 26,1924 3 Sheets-Sheet 1 51m uc H To: Jafzzwiflmizdeizhryez" Quorum Nov. 161926. 1,606,824

J. E. BRANDENBERGER DRYING 7 VCELLULOS E FILMS Filed Jan. 26, 1924 3Sheets-Sheet 2 Snow,

Nov. 16 1926.

1,606,824 J. E. BRANDENBERGER DRYING CELLULOSE FILMS Filed Jan. 26, 19243 Sheets-Sheet 5 anuewtoz Patented Nov. 1a, 1926.

UNITED STATES PATENT OFFICE.

JAQUES EDWIN BRANDENBERGER, OF NEUILLY-SUB-SEINE, FRANCE, ABSIGNOB TO LAsocrfirfi: LA GELLOPHANE SIEGE S;OCIA.L, F LOUVRE, FRANCE.

DRYING CELLULQSE FILMS.

Application filed January 26, 1924, Serial No. 688,873, and in FranceFebruary 12, 1923.

This invention relates to improvements in drying cellulose films ingeneral, and more particularly cellulose films derived from aqueoussolutions of cellulose such, for in- 5 stance, as an aqueous solution ofsodium cellulose xanthate.

The possibility of continuously producing cellulose films is commonknowledge,the said films being rolled up in rolls in pro- 1" portion asthey are manufactured, the film on each roll being-as long as desired.Cellulose films are industrially utilizable if they are dried afterbeing manufactured, but the drying of the films, however, involves greatdiificulties in practice. If merely exposed to the air, the cellulosefilm shrinks, shrivels up, loses most of its transparency and becomes oflittle value for industrial purposes. It has also proven unsatisfactoryto anchor or hold in fixed position the edges of the film while itisdrying, as this results in cracks and breaks in the film either whiledrying or when it is removed.

Attempts have been made to obviate these disadvantages by means ofmachines which act to prevent the film from shrinking while it isdrying; in these machines the film was held at all points by means ofelements which did not compress it to any marked ex- 39 tent butm'erelyheld both faces of the film in contact with'tl1'e rigid surfaces of thesaid elements. "lTo that end, the film was fed between a series ofcylinders rollingover one another and arranged so that one or the otherface of the film was constantly in contact with the surface of one ofthe cylinders. This method of proceeding did prevent the film fromshrinking, but was not altogether satisfactory, for instance inasmuch asthe surface of the film was scored owing to the pressure, even thoughslight, exerted by the cylinders thereon.

The present invention relates to a. method of drying which obviatesthese disadvantages, and it also involves an apparatus for carrying thesaid method into practice.

The improved method or process is based on the following observations:It has been found that if the cellulose film, while it is drying, iscontinuously passed over cylinders without either of the faces of thesaid film width, the extent of shrinking being dependent upon the lengthof film which at a. certaln time is not in contact with any cylinder, i.'e., upon the distance apart of the cylinders. The process according tothis invention consists, therefore, in drying the cellulose film bycausing it to pass over a series of cylinders or rolls which exert nopressure upon the film but merely guide it, with the result that a filmis produced which is perfectly smooth, remarkably transparent and whichis uniformly shrunk relatively to its initial dimensions, the shrinkinbein accurately predetermined by suita ly a justing the clearancebetween the rolls.

Heretofore the film was altogether prevented from shrinking by thepressure to which it was subjected, which pressure, even when as slightas it could possibly be made, detrimentally' affected the final product.Aecordin to the present invention, the film is dried without theexertion of any pressure thereon, and it is allowed to shrink uniformlyto an accurately predetermined extent.

The process maybe carried into practice by means of any suitableapparatus, but preferably by means of that subsequently described, whichcomprises a series of driving rolls adapted to rotate another series ofrolls, the working faces of these rolls (i. e. the faces on which thefilm is carried) having no point of contact with each other so that thefilm is at no time under any pressure. To accomplish this, both ends ofeach roll, at points beyond the portion with which the fi lm comes incontact, are fitted with rings or flanges forming arolling track. theends of the driven rolls resting on the driving rolls through the mediumof these rings which serve the purpose of providing a clearance betweenthe working faces of ad- 5 jacent rolls and which also afford the meansfor driving one set of rolls from the other set, as well as forpreventing endwise displacement of the rolls.

An apparatus whereby the process according to this invention may becarried into practice is illustrated by way of example in theaccompanying drawings, in which:

Figure l is an end elevation showing a number of the rolls of theapparatus.

Figure 2 is a diagrammatic cross-section through the centres of the saidrolls and also through the winding mechanism.

Figure 3 is a partial detail view of two rolls, looking from line 3-3 ofFig. 1.

Figures 4 and 5 illustrate a method of rotating the drivin rolls andmeans for circulating heated uid such, for example, as air in some ofthe rolls.

Figures 6 and 7 show details of the winding mechanism.

The apparatus represented comprises a set of rolls 1 rotated by anydesired means in the direction of the arrows. Each end of each of therolls has a ring or flange 2 forming a rolling track. Each of the drivenrolls 3 is likewise fitted at each of its ends with a ring or flange 4.The rolls 1 are set at a suitable distance apart, and the rolls 3 restwith their rings or flanges 4 on the rings or flanges 2 of the rolls 1,as shown in Figures 1 and 3. The rolls 3 are supported on, and drivenby, the rolls 1 and rotate in the direction of the arrows. A clearanceis provided between the working faces of all these rolls, the amount ofclearance depending upon the thickness of the flanges 2 and 4. There isno point of contact between the working face of one roll and that ofanother roll.

The cellulose film 5 to be dried is engaged between the various rollsand is carried and fed by the same, as shown in Figures 1 and 2. Thefilm is not compressed between the rolls owing to the gap or clearancebetween the latter, and at any one time a portion of the film is incontact with the face of the rolls 1, another portion is in contact withthe face of the rolls 3 and a further portion is not in contact witheither set of rolls. The last-mentioned portion is the one that shrinkswhen drying and which causes a final uniform shrinking of the filmsubjected-to drying if care is taken to move the film along at uniformspeed and to render the drying uniform. The system of rolls, thecomponent members of which may be arranged in one or more tiers orsuperposed rows, is preferably located in a closed chamber forming akind of drying room or enclosure, the temperature of which may be raised(either by direct heating or by circulating a fluid) to the desiredextent for the purpose of properly drying the cellulose film to betreated.

The drying apparatus may be used separately for drying a cellulose filmpreviously wound up in a roll, or it may be used in combination with themachines for manufacturing and manipulating the said film, i. e., incases where the film is not fed to the drying apparatus from a storagedrum or roll, but straightaway from the said machines In any case,however, the film coming from the apparatus herein described will befound to be dried and uniformly shrunk and may be wound up on a suitablyrotated receiving drum. I

One of the essential features of the invention consists in driving therolls 1 by resilient or elastic means of any suitable kind,

for instance a slip drive, as opposed to a above described, but alsolongitudinally. If,-

now, the driving rolls were rotated by rigid or positive driving means,the film would be subjected to tension and would break owing to the factthat the longitudinal shrinking is not the same at the various points ofthe apparatus.

for the shrinliing of the film, and the rotating of these rolls to bedetermined in whole or in part by the linear motion of the film, whichmakes necessary a slipping, resilient, or elastic drive. The latter maybe of an desired type'; for instance, a belt drive wit 1 belts adaptedto slip on the pulleys.

Figs. 4 and 5 illustrate by way of example a belt-and-pulley drive. Eachof the rolls 1 is carried on a shaft 6 supported in suitable bearingsfitted to the-walls of the drying chamber, and a pulley 7 is keyed toone end of each shaft externally to the said chamber. A main shaftv 8,driven in any desired manner, is adapted to drive through suitablegearing 19, or in some other preferred way,aseries of shafts 9 allparallel to the shafts 6 and equal in number to half the number ofrolls 1. Each shaft 9 rotates two rolls, and is provided to that endwith two rigidly secured pulleys 10 and 11. The pul- It is thusnecessary to allow the speed of the driving rolls to compensate ley 10drives, through a belt-12, the pulley 7 of one of the rolls 1, and thepulley 11, through the medium of a belt 13, drives the pulley 7 of thefollowing roll, (Figs. 4 and 5). The tension of the various drivingbelts 12, 13, etc. is so adjusted that the belts are adapted to slip ontheir pulleys for the purpose of producing the required give orelasticity.

On leaving the last drying roll, the film passes to a mechanism whichwinds it up and which also serves to maintain it under tension duringits passage through the drythereafter wound up on another mandrel.

The mechanism per se forms no part of the actual invention and anymechanism suitable for the purpose may, therefore, be employed. The oneillustrated is that which is regarded as preferable and, as shown, it

ill!

comprises a set of friction ears 22 in driving engagement with otherriction gears 23, of which there is one for each of the mandrels 20. Thegears 22 are loosely mounted on stub shafts 24 secured to one of thestandards 21; and one of these gears, in this instance the upper one,has rigidly connected to it a pulley 25 driven by a belt 26 from alarger pulley 27 which is fixed to a horizontal shaft 28 also journaledat one end in the standard, shaft 28 being connected by a suitableintermeshing gears 29 to the main shaft 8 to be driven therefrom.

The mandrel spindles are disposed in horizontal co-planar relation withhorizon tal stub shafts 30 on which the gears 23 are loosely mounted andwhich are alsofastened to the standard; the gears 23 having associatedwith themv similar gears 31 in mesh with.and driving gears 32 on themandrel spindles. The cooperating gears 28 and 31 are related by deviceswhich function as slip clutches to variably couple them together, andmeans are provided for regulating the action of these clutches! In theconstructionillustrated, leather disks 33 are employed, and a presserplate 34 is splined on the stub-shaft 30 in' position to bear againstthe outer face of gear 23 and is subjected to the action of acoil spring35 which encircles said shaft and the tension of which is adjusted by ahand wheel 36 or the like.

It will be apparent, therefore, that by properly adjusting thecorresponding hand wheel, the degree of frictional coupling between anypair of gears 23 and 31 can be regulated at will from a maximum in whichthe two gears rotate at the same speed with no slippage whatever, to aminimum in which gear 23'virtually rotates idly and transmits no motionto its associated gear 31. The latter gear, assuming that it is in meshwith the gear 32 on the mandrel which is being filled, determines thespeed of rotation of the mandrel and, hence, the tension exerted on thefilm during the winding operation, thus permitting the tension to beregulated in accordance with the increasing diameter of the roll of filmon the mandrel.

The rolls 1,moreover, may be utilized to assist in, or to supplement,the drying action above described. Hollow rolls may be resorted to forthis purpose, and may be heated either directly or by circulating aheated fluid therein, or in any other convenient manner. Heated fluidmay be supplied to the various rolls 1 through headers 14 and suitablepiping 15 (Fig. ,5). The temperature to which the rolls are heated mustbe regulated so as not to produce, at any point of the drying apparatus,a layer or film of steam between the cellulose film and the heating faceof the roll, as this would have the serious drawback of doing away withcontact and, therefore, adherence between the said cellulose film and ofthe roll, the conse and unforeseen shrin The outer casing or dryingchamber surrounding the ro s may be dispensed with in an apparatusfitted with internally heated rolls as described; but the casin isnevertheless advantageous inv that it afl brds the possibility ofaccelerating the drying operation by enabling the circulation of heatedair therethrough.

The film shrinks transversely in accordance with the thickness of theflanges 2 and 4, so that it is possible to construct a'machine which,for a given thickness of flange or ring and under definite conditions ofdrying, yields a filmshrunk to a predetermined extent. Rolls may be usedthe flanges or rings of which are removable and, therefore, adapted tobe replaced by rings of another thickness in order to shrink thematerial to various degrees in the course of the drying operation.

It is understood that the above-described structural details are merelygiven by way of example and do not limit the scope of the invention.

I claim as my invention:

1. Apparatus for drying continuous celluthe heating face ing of thematerial.

lose films, comprising two separate sets of coact-ing rolls around whichthe film is fed, means for driving one set, and mutuallyengaging ringson the opposite ends of contiguous rolls of the two sets for driving theother set from the first set while maintaining the working surfaces ofthe contiguous rolls of both sets out of contact with each other,thereby to support and'guide the film without subjecting it tocompression; substantially as described.

2. Apparatus for drying continuous cellulose films, comprising twoseparate sets of coacting rolls around which the film is fed, mechanismincludin slip-driving devices for rotating the rolls of one set, andmeans for driving the rolls of the other set from the first set;substantially as described.

3. Apparatus for drying continuous cellulose films, comprising twoseparate sets of coacting rolls around which the film is fed, mechanismincluding slip-driving devices for rotating the rolls of one set,andmeans for driving the rolls of the other set from the first set whilemaintaining the working surfaces of contiguous rolls of the two sets outof mutual contact, thereby to support and guide the film withoutsubjecting it to compression; substantially as described.

4. Apparatus for drying continuous cellulose films, comprising a set ofdriving rolls, a set of rolls coacting with the driving rolls and driventherefrom, the two sets of rolls conjointly feeding the film betweenthem, a main drive shaft, a series of driven shafts connected therewith,and slip-drive connecuence being an undue tions between each drivenshaft and} two of- (i'AbParatus. for drying continuoustcel 15 thedriving rolls. 5. Apparatus lulose films, comprising a set of drivingrolls;

a set of driven rolls, mutually-engaging rings on the opposite ends ofcontiguous driving and driven rolls to operate the latter from theformer and to maintain their working surfaces in spaced relatiornthe twosets of rolls conjointly feeding the film between them, a main driveshaft, a series of driven: shafts connected therewith, and slip-driveconnections between each driven shaft and two of the driving rolls.

' i for drying continuous cel;

lnlose films, comprising a set of driving rolls, a set of rolls coactingwith the driving rolls and driven therefrom, the two sets of rollsconjointlyfeeding the film between them, a main drive shaft 'a series ofdriven shafts connected therewith, slip-drive connections between eachdriven shaft and two of the driving rolls, and mechanism for Winding upthe film and exerting a variable tension thereon.

In-testimony whereof I afiix my signature.

.JAQUES tnwm BRANDEhBERcER.

